Yttrium(II) oxide or yttrium monoxide is a chemical compound with the formula YO. This chemical compound was first created in its solid form by pulsed laser deposition, using yttrium(III) oxide as the target at 350 ðC. The film was deposited on calcium fluoride using a krypton monofluoride laser. This resulted in a 200 nm flim of yttrium monoxide.